Electronic contrast area ratiometer



y 31, 1956 E. c. BOYCKS ELECTRONIC CONTRAST AREA RATIOMETER 4Sheets-Sheet 1 Filed April 1, 1952 I00 KC PULSE GENERATOR MANUAL WITCHILANKINO IRUSN PULI COUNTER PULSE OAT! PULlI COUNTER SGANNINO HEADIZTIEWZZIT Edward C? Boycfns y 31, 1956 E. c. BOYCKS v 2,756,627

ELECTRONIC CONTRAST AREA RATIOMETER Filed April 1, 1952 4 Sheets-Sheet 2Eda/cam C B0 yaks United States Patent ELECTRONIC CONTRAST AREARATIOMETER Edward C. Boycks, Madison, Wis., assignor to Neltoosa-Edwards Paper Company, Port Edwards, Wis., a corporation of WisconsinApplication April 1, 1952, Serial No. 27 9,861 7 Claims. (Cl. 88'14)This invention relates to means for obtaining a numerical countproportional to the area of an object having light reflective propertieswithin a preselected range, and is directed particularly to a device andmethod for evaluating the actual volume of wood in a stack.

Pulpwood evaluation has long been recognized by the paper industry asbeing essential to the most economic utilization of this valuable rawmaterial. In general, the problem has been that of adapting suitableevaluation methods to the wood receiving and handlin methods of theindividual mill. Inland mills that receive their supply of pulpwood byrail, truck, or both, are faced with the often discouraging problem ofobtaining representative samples at a cost in keeping with the value ofthe Wood.

In the manufacture of pulp for paper the factor having the greatestinfluence on the value of the purchased cord is the amount of soundsolid material contained in this unit of measure. In mills where a largepercentage of the supply is obtained from small operations in widelyscattered areas and the pulp wood is in the form of relatively shortbolts, the problem of determining actual wood volume and the percentageof sound wood is particularly diflicult. Thus, the need for a quick,inexpensive, yet reasonably accurate method for making suchdetermination is of paramount importance in the industry today. Theweight of wood can, of course, be determined by Weighing, but this isfrequently impractical and also requires that the moisture content ofthe wood be taken into consideration. A system of sampling for moisturewould be necessary for a mill receiving seasoned and partially seasonedwood if the supply was to be purchased on a weight basis. By reason ofthe varying moisture content of the wood and various other difficulties,the direct weighing of the wood has been regarded as impracticable.

However, from tests on previous shipments of wood of the same speciesfrom the same locality, the specific gravity of the wood on an oven-drybasis can be determined. Knowing this specific gravity, the weight ofthe wood can be determined if the actual wood volume in the cord orshipment is known. It has been found that the actual wood volume in anominal 128 foot cord may vary between approximately 80 and 105 cubicfeet depending on the species of Wood, the average diameter and thedistribution of the individual diameters of the sticks, and many otherfactors. The determination of the actual wood volume by customarymethods is dilficult and usually is based on either estimation by anexperienced scaler or by some method of measurement on a sample quantityof wood selected from the entire lot.

it is the primary object of the present invention to provide means bywhich this actual Wood volume can be determined quickly and accuratelyand with a reasonable amount of labor, both in handling the wood and indeter mining the volume, and with the least delay in handling shipmentsof wood as they are received.

Heretofore, in the patent to C. H. Keepers, No. 2,424,619, issued July29, 1947, it has been proposed to evaluate the actual volume of a stackof wood by photographing the butt ends of the logs and then measuringthe area of the butt ends by means of a manually operated geometricalmachine.

It is an important object of the present invention to provide novelmeans for obtaining a numerical count proportional to the area of thebutt ends of logs in a photograph by automatic electronic canning.

it is a further important object of the present invention to providemeans for determining the actual volume of wood in a stackelectronically in an extremely rapid manner, while yet obtaining highlyreliable results.

It is a still further object of the present invention to provide meansfor obtaining a numerical count proportional to the volume of Wood in astack which is extremely simple and which involves a minimum of effortand strain on the part of the operator.

It is a more specific object and feature of the present invention toprovide means for obtaining a numerical count indicating the proportionof the area of a photograph having light reflective properties within apreselected range utilizing a synchronously rotating scanner drum and anaxially moving scanning head.

It is a further more specific object and feature of the presentinvention to provide means for obtaining a numerical count indicatingthe proportion of the area of a photograph having light reflectiveproperties within a preselected range utilizing in combination anelectronic gate or coincident pulse determining circuit and a bank ofelectronic counters.

It is a still further more specific object and feature of the presentinvention to provide means for obtaining a numerical count indicatingthe proportion of the area of a photograph having preselected lightreflective properties utilizing in combination a synchronous rotatingscanner drum, an axially movable scanning head, and an elec tronic gateor coincident pulse determining circuit controlled by said scanning headto permit actuation of a battery of electronic counters while said headis scanning an area having the selected light reflective properties.

It is a more general object and feature of the present invention toprovide means for obtaining a numerical count indicating the proportionof the area 'of an object having light reflective properties Within apreselected range, said means comprising photoelectric means forscanning said object, an electronic signal generator, an electroniccoincident signal determining circuit receiving signals from said signalgenerator and from said photoelectric means, and a counting deviceconnected to the output of said coincident signal determining circuit,said coincident signal determining circuit passing signals from saidsignal generator to said counting device upon coincidence of signalsfrom the signal generator and from said photoelectric means.

It is a further more general object and feature of the present inventionto provide means for obtaining a numerical count proportional to thearea having light reflective properties above or below a certainreflectivity of a photograph, comprising photoelectric means forscanning said photograph, an electronic pulse generator, an electronicgate which is open to flow of pulses When actuated by input signals fromsaid photoelectric means of above a preselected level and closed for allinput signals of below the preselected level, means for varying saidpreselected level, means for transmitting the output of saidphotoelectric means during scanning to said electronic gate to controlthe opening and closing of the electronic gate, a counting device, andmeans for actuating said counting device connecting with said countingdevice through said electronic gate and controlled by said electronicgate to actuate said counting device only when the gate is open.

it is a specific feature of the present invention to provide a novelscanning limit control system.

It is a further specific feature of the present invention to provide incombination a novel scanning limit control system and scanning limitindicator circuit.

It is a further specific object of the present invention to provide anovel system for determining the range of light reflectivity of anobject being scanned for which a numerical count is to be obtained.

It is another specific feature of the present invention to provide anovel electronic contrast area rationieter.

Other objects, features, and advantages of the present invention will bereadily apparent from the following detailed description of a preferredembodiment thereof taken in view of the accompanying drawings.

On the drawings:

Figure 1 is a front elevational view of an electronic contrast arearatiometer constructed in accordance with the principles and features ofthe present invention;

Figure 2 is a block diagram indicating the relation between some of thebasic components of the electronic contrast area ratiometer shown inFigure 1;

Figure 3 is a fragmentary perspective view of the blanking brushcomponent utilized for determining the circumferential scanning limitsof the scanning system;

Figure 4 is an enlarged fragmentary perspective view of the centralexterior of the electronic contrast area ratiometer shown in Figure 1;

Figure 5 is a more detailed block diagram indicating the relationbetween the various component parts of the electronic contrast arearatiometer of Figure 1;

Figure 6 is a diagrammatic representation of the scanning head and pulsegate portion of the electric circuit of the electronic contrast arearatiometer;

Figure 7 is a diagrammatic indication of the pulse generator, blankingbrush, and limit indicator circuits of the electronic contrast arearatiometer; and

Figure 8 is a fragmentary view of a portion of a high contrastphotograph such as used with one electronic contrast area ratiometer.

The arrangement of the components of the electronic contrast arearatiometer or ECAR will be apparent from Figures 1, 3 and 4. Referringespecially to Figure 1, the ECAR is designated generally by thereference numeral 10 and comprises a cabinet frame 11 receiving aplurality of superimposed component units which may be individuallyremovable and replaceable. These component units include a centralscanning section 12, upper counting units 13 and 14, and a lower mainpower unit 15.

Centrally of the frame 11 is the scanner drum 18 which is rotatablymounted in a protruding housing 19 in front of the scanning section 12.The housing partially encloses and serves as a guard for the rotatingdrum. In Figure 1, two photographs 20 and 21 are shown mounted about theperiphery of the drum.

Photographs These photographs may be of the butt ends of a stack of logspiled in a railroad freight car or other transporting vehicle. If thesides of the car obscure a portion of the stack it has been found that asuflicient sampling of the stack can be obtained from a photograph ofthat part of the stack projecting above the sides of the car. How ever,railroad cars constructed expressly for shipping pulpwood are nowbecoming available and these cars have open sides to expose the ends ofevery log in the stack.

The object of the ECAR is to obtain the percentage of wood in the volumeoccupied by the stack. Then from a knowledge of the stack volume, thevolume of solid wood may be computed. One method of determining thevolume occupied by the stack is by photographing the serial number ofthe car as well as the stack of logs therein. From the serial number,the length and depth of the car can be obtained from the, railroad. .The

4 length of the logs is customarily taken at 96 inches. The height ofthe stack above the side of the car could be measured on the photographand converted into actual height, or the area of the stack above the carcould be measured with a planimeter.

The percentage of wood in the volume occupied by the stack is obtainedby the ECAR by a process of photoelectric scanning. In this process, asmall spot of light is moved over the photograph and light reflected bythe photograph is viewed through an image limiting orifice and amicroscopic objective by a photoelectric device. As seen in Figure 1,the butt ends of the logs appear white in the photograph while the voidsor spaces between the logs appear black. When the scanning spot of lightimpinges on a white or wood area on the photograph, a relatively largeamount of the light is reflected by the photograph and detected by thephotoelectric device. When, however, the spot falls upon a black or voidarea on the photograph, relatively less light is reflected to thephotoelectric unit.

By electronic means, the photoelectric cell is made to control anelectronic counter, so that the counter will register the relativeamount of white or black area on the photograph.

It will be apparent, therefore, that a high contrast photograph having aminimum of intermediate gray tones is desirable when the ECAR is to beused for determining the percentage of wood in a stack. Also it will beapparent that shadows on the ends of the logs should be avoided duringthe photographing. When the photography is carried out with conventionalcameras, it has been found desirable to make two photographs of eachcar, one of each end, so that the logs are viewed more nearly at rightangles to the cut end faces or butt ends thereof. Also, a telephoto lensis useful in permitting the photography at a greater distance.

Scanning From the above description of the photographs and of how thepercentage of white or black on the photograph is detected by moving asmall spot of light over the photograph and detecting the amount of suchlight which is reflected from the photograph, it will be understood thatmeans must be provided for moving the spot of light and photoelectricdetector over the photograph, or scanning the photograph.

In the ECAR, a photograph is scanned by mounting the photograph on thecylindrical scanner drum 18 and rotating the drum to move the photographpast the spot and photoelectric unit to scan one dimension of thephotograph, while the spot and photoelectric cell constituting thescanning head are slowly moved axially along the drum to scan the otherdimension of the photo graph. Actually, therefore, the scanner headpreferably moves in a helical path relative to the drum and moves acrossthe photograph in a series of spaced paths or lines.

The precise construction of the scanning head utilized in the ECAR formsno part of the present invention and will not therefore be described indetail and has not been shown in the drawings. A scanner head such ascommonly used in the field of facsimile transmission has been found tobe satisfactory. A typical facsimile scanner head is shown in the U. S.Patent No. 2,560,614, to La Verne C. Walker, dated July 17, 1951.

Such a scanner head is mounted on rails extending parallel with the axisof the drum 13. The drum is driven by a synchronous motor. and thescanner head is moved along its mounting rail in synchronism with therotation of said drum to advance slightly along said rail with eachrevolution of the drum. In the ECAR there is a slot 24 in the front wall2:! of the scanner section 12, Figure 4, so that a segment of therotating drum is exposed to the scanner head traveling horizontallyacross the Width of the drum within the cabinet. Since the mounting of ascanner head on a rail to move axially along a rotating drum is wellknown in the facsimile transmission art and does not per se form a partof the Figure 2 illustrates the general arrangement of the majorelectronic components according to the present invention. It will beobserved that a pulse gate 27 is utilized. This component acts tocontrol the flow of electric pulses from the pulse generator 28 to thepulse counter 29. When the pulse gate 27 is open, pulses flow from thepulse generator to the pulse counter 29 and are there counted. A visualindication of this count may be obtained partly by means of theelectromechanical register 30 seen in Figure 1 in the uppermost countingsection 14. When the pulse gate 27 is closed, pulses from the pulsegenerator do not reach the pulse counter and therefore are not counted.

As indicated diagrammatically in Figure 2, scanning head 32 controls theopening and closing of the pulse gate 27. Thus, for example, the ECARcan be adjusted so that, when the scanner head 32 is scanning a whitearea on the photograph 20, the output from the scanner head will causethe pulse gate 27 to open, while when a black area is being scanned, thepulse gate will remain closed. The pulse counter 29 will thus give anumber indicative of the amount of white area on the photograph, or theactual solid wood area in the stack. If now the total number of pulsesgenerated by the pulse generator during a scanning operation is known,the percentage of white area on the photograph can be readilydetermined. The preferred manner of obtaining this total pulse count isby means of a second total pulse counter 34, Figure 2, connected to thepulse generator ahead of the pulse gate 27 so as to receive all pulsessent out by the pulse gen erator 28. This total pulse counter 34 ishoused in the counting unit 13 in Figure 1 and includes the electromechanical register 35 seen in Figure 1.

In the present embodiment of the invention, a manual switch 35 serves toapply pulses from the pulse generator to the input of the pulse gatewhen the scanning head has reached the portion of the photograph whichis to be scanned, and to interrupt the pulses to the pulse gate when thehead has covered the area of the photograph to be scanned. The switch 35thus controls the axial scanning limits of the head across the width ofthe photograph.

Since the photograph will not extend entirely around the circumferenceof the drum, it is also necessary to interrupt the pulse generator whilethe head is scanning between the ends of the photograph on eachrevolution of the drum. These circumferential scanning limits arecontrolled by the blanking brush 36 indicated schematically in Figure 2.

Pulse generator The pulse generator, as indicated in Figure 7, may be ofthe tuned-grid tuned-plate type with a 100,000 cycle per second crystald0 supplying the grid tuned circuit. A grid resistor shunts the crystaland is connected between the control grid of the pentode tube 43 and thecathode thereof. The tuned-plate circuit includes fixed inductance fixedcapacitance 45 and a variable capacitance 46. The plate voltage issupplied from the conductor 47, the screen grid voltage being providedthrough resistor A by-pass condenser is connected be tween the screengrid and cathode and a further by-pass condenser is connected from theplate tuned circuit to ground. The pulse generator may be enclosed in asoft iron shield indicated by the dash line 52.-

The output from the pulse generator is taken across the resistor whichmay for example have a resistance of 250 ohms. The output is deliveredto a phase inverter and cathode follower circuit by means of conductors57, 58 and 59 and to the pulse gate circuit through conductors 57, 58and 60.

Manual switch The significance of the manual switch 35 in Figure 2 maynow be understood. This block in the diagram of Figure 2 corresponds tothe scanning control switch 63 shown in Figure 7 and is the centerswitch 64 in Figure 1.

One section of the switch is connected to the high end of the pulsegenerator cathode resistor 55 through conductors 57' and 65. In thelower position of switch 63 as seen in Figure 7, the resistor 55 isshorted out through conductors 57, 65, switch 63 and conductor 66 sothat there is no output from the pulse generator. It will be understood,however, that the pulse generator continues to oscillate and that itsoperation is not substantially affected by shortiru out resistor 55because of the low resistance thereof. In the upper position of switch63, the high end of resistor 55' is connected to the brush 67 of acommutator or blanking brush assembly 69. This commutator assembly 69corresponds in the block diagram of Figure 2 to the blanking brush block36. The other section of switch 63 serves to connect the commutatorbrush 67 to the limit indicator conductor 70.

The method of determining the axial limits in the present embodiment ofthe ECAR will now be understood. After the photograph has been mountedon the scanner drum 18, for example with the long axis of the photographextending around the circumference of the drum, the scanning headexciter lamp is turned on (by switch 71 in Figure 1) so that a spot oflight will be visible on the drum. in the present ECAR the scanner headcarriage may be disengaged from its drive and moved axially along thedum until the spot of light from the exciter lamp of the scanner headstrikes the left border of the area on the photograph to be scanned. Theposition of the scanning head at this time is indicated by pointer 73,Figure 4, which is mounted on the scanning head carriage and projectsthrough the slot 24 in scanning section 12. A scale strip 74; is mountedon the front wall 25 of the scanning section 12, Figures 1 and 4, foraccurately indicating the position of the head. The scale readingcorresponding to the left limit on the photograph is recorded and thescanner head carriage is moved to the right border of the area to bescanned. The right limit scale reading is also recorded. In the case ofphotographs of a stack of wood, the limits are chosen so that the dot oflight from the scanner head is well within the wood area, so that anaccurate sample will be obtained.

To begin scanning, the head is moved to the left of the left scanninglimit on scale 24 and the scanner drum driving motor is turned on (byswitch 77 in Figure 1). When the pointer 73 reaches the left limit onscale 74, the scanning switch 64 is thrown to move manual switch 63 inFigure 7 to the upper position. In this position the output from thepulse generator is not shorted out through conductors and 66, so thatpulses are delivered to the pulse gate 27 and pulse counter 34 (Figure2) under the control of the blanking brush assembly 69 as willhereinafter be described. When the pointer 73 reaches the right scanninglimit the center switch 64 in Figure 1 is thrown to move switch 63 inFigure 7 to its lower position to short the output resistor 55 oncemore.

It will be understood that the manually controlled axial scanning limitscould be controlled automatically by the use of limit switches. Thus theleft and right scanning limits would be selected by suitable adjustmentof a pair of knobs which in turn would position the limit switches. Thescanning head would then be pushed against the left limit switch andfrom this point operation would be completely automatic. After amomentary contact push button had been depressed, the drive motors wouldstart, scanning would begin and would cease at the proper positions ofthe scanning head, and the drive motors would shut off at the completionof the run.

When the photograph shows all the sticks as would be the case with arailroad car having open sides, the white count is proportional to thetotal wood volume. Thus, the white count is simply multiplied by asingle proportionality constant to obtain total wood volume, without thenecessity for knowing the stack volume or dimensions of the car.

Blanking brush The blanking brush assembly is best shown in its physicalstructure in Figure 3 and comprises commutator drum 82 which is mountedfor rotation with the scanner drum 18. The function of the assembly isto automatically control the circumferential limits of scanning, that isto blank out the pulse generator during the time when the scanning headis scanning between the ends of the photograph. To accomplish this, theblanking brush assembly will ground the high end of the output resistor55 of the pulse generator while the scanning head is scanning off thephotograph, so that no pulses will arrive at the pulse gate 27 in Figure2 or the pulse counter 34. Referring to Figure 2, the blanking brush 36thus acts effectively as a valve allowing pulses to flow through onlywhile the scanning head 32 is scanning a certain selected portion of thecircumference of scanner drum 1%.

The purpose of the blanking brush is thus to adjust scanning forditierent length photographs. For convenicnce one end of the area isalways positioned at the same location on the drum 18 and the other endof the area to be scanned will thus fall at different positions aboutthe circumference of the drum 18. The commutator drum 82 is made ofconducting material, but has a portion of its curved surface routed outand filled with a non-conducting material. As seen in Figure 3, theportion 33 of the curved surface is conducting while the portion 84 isnon-conducting. The conducting surface portion 83 has a generallyhelical inner margin 86 and a straight axially extending margin 87 atone end. The cylinder may for example be made of brass and the routedportion filled with an acrylate polymer.

For grounding the high end of the output resistor 55, the conductingportion of the commutator cylinder 82 may be grounded by means of a ringon the shaft 91 and a brush connected by conductor 92 to ground asindicated in Figure 7. The commutator brush 67, Figures 3 and 7, isadapted to make contact with the circumference of the drum and to begrounded while contacting the conducting portion 83 thereof to blank"out the pulse generator output. The straight margin 27 of the conductingportion 83 thus establishes one circumferential scanning limit, whilethe other circumferential limit depends on where the brush 67 strikesthe generally helical margin 86 of the conducting portion 83.

The second limit may be adjusted by shifting the brush 67 axially alongthe commutator drum. To this end the brush 67 is carried on a block 94which is axially adjustable by means of a threaded shaft 95 to which issecured adjustment knob 97. The knob $7 and pointer 98 carried by block94 are visible in Figures 1 and 4, respectively, since they projectthrough the blanking brush casing 9 which normally encloses the blankingbrush assembly. The lead 100 connecting the scanning switch 63 to thebrush 67 is coiled to permit the axial movement of brush 67.

it will be understood that with the blanking brush described. one end ofthe area of a photograph to be scanned is positioned on the drum tocorrespond to the margin 3'7, while the brush 67 is adjusted to justcontact the helical margin $6 at the other end of the margin to bescanned. This latter adjustment is facilitated by the limit indicator.

Limit indicator The relation of the limit indicator to the other ECARunits is indicated generally in Figure 5, the reference numeral 101designating the limit indicator and 102 desigcat nating its powersupply. As seen in Figure 7, when the scanning control switch 63 is inits lower position, the commutator brush 67 is connected to the limitindicator lead 7 0. The limit indicator circuit includes a neon bulb 1&3which is caused to glow when the brush 67 is contacting the conductingportion 83 of commutator drum 69. Voltage is supplied by an isolationtransformer 104 through resistance 105. The bulb is visible from thefront of the ECAR cabinet just above the scanner section 12.

Thus to determine the variable circumferential scanning limits, thephotograph is mounted on the drum with one end of the area to be scannedfixed in an angular position to coincide with the straight margin 87 onthe commutator 82. The exciter switch 71 is then closed to cause thescanning spot to shine on the drum. The drum is then rotated until thespot strikes the other end of the area of the photograph to be scanned.The knob 97 is now turned to move the brush 67 to the helical margin 86of the commutator 82; at this point the limit indicator bulb 103 shouldgo on and off as the knob 7 is turned slightly back and forth. Thecircumferential scanning limits are now established and the commutatordrum will automatically blank out the pulse generator during the portionof each revolution of the scanner drum when the scanning beam is off thearea of the photograph to be scanned.

Total pulse counter One arrangement of circuits comprising the totalpulse counter 34 of Figure 2 is indicated in the block diagram in Figure5 and comprises a phase inverter 110, cathode follower 111, pulseshaping circuit B, 112, binary sealers 113, cathode follower 114,electronic counter and electromechanical register 116. it will beunderstood, however, that this particular arrangement is describedmerely by way of example and not by way of limitation, since many othercounting circuits could be utilized. Furthermore, a total pulse counteris not necessary, for example, if a fixed area is to be scanned forwhich the total number of pulses can be computed, or if an all white orblack calibrating photograph is first scanned using the selectedscanning limits so that the proportion pulse counter 29 may be employedto obtain the total count.

Phase inverter and cathode follower Since the output of the pulsegenerator, in the present embodiment, consists of a series of positivepulses While the driving circuit 112 for the scaling units 113 requirenegative pulses, the phase inverter stage 110 has been utilized. Asuitable circuit has been shown in Figure 7 and include a twin triodetube 120. The output from the pulse generator is fed into the grid ofthe first triode stage by conductor 59. The plate voltage is supplied tothe tube from conductor 122 through resistor 123, and the grid bias isadjusted by means of fixed resistor 124 and potentiometer 125, thecathode lead 127 being connected to the moving contact of thepotentiometer. The output from the tubes first stage is delivered to thegrid of the second stage by means of conductor 128, capacitance 130, andconductor 131. The resistors 134, 135 and 136 suitably adjust the gridbias for the second stage of tube to operate as a cathode follower, theoutput being taken from the cathode by conductor 137.

The cathode follower stage represented by block 111 in Figure 5 isutilized to decrease the impedance of the output of the preceding stageso that a relatively large current drain or the like will not alter thewaveform of the output signal. All the cathode follower stages utilizedin the present embodiment have substantially this purpose.

Other pulse counter units The binary sealers 113 utilized in the presentECAR (manufactured by the General Electric Company as type 4SNlA3) arescale-of-two counters and are used to scale down the pulses from thepulse generator to within the maximiun speed of the mechanical register116. The

9 total number of counts presented to these units 113 may be read byindicator lamps. The pulse shaping circuit B, 112, is a driving circuitfor the binary scalers sug gested by the manufacturers.

The cathode follower 114 functions to prevent overloading and the likeand may utilize a conventional circuit.

The electronic counter 115 at present comprises three decade scalingunits (furnished by the Potter Instrument Company, Inc. as model No.330). The pulse shaping circuit for these units was found to beunnecessary. The counter 115 is arranged to form a scale of 1000. Sinceeach binary scaler allows only one out of two suitable pulses whichenter it to pass, and there are three binary 'scalers, only one out ofeight pulses will reach the counter units. At 100,000 pulses per second,12,500 pulses will thus reach the electronic counter 115. These unitsscale the 12,500 down by 1000 so that only 12.5 pulses per second reachthe mechanical register 116. (The electromechanical register used in thepresent embodiment is manufactured by the Atomic Instrument Company asmodel 1238.) Since counter 115 can be read by means of neon lamps, it ispossible to read three significant figures from the units used in theembodiment disclosed in addition to those displayed by theelectromechanical register.

Reset relay The reset relay shown in Figure 5 comprises a relaypossessing four separate sets of contacts, two make and Scanning headcircuit As seen in Figure 5, the present embodiment, the scanning headcircuit includes a photomultiplier tube 145, power supply 146, cathodefollower 147 and bias supply 149. Referring to Figure 6, the electriccircuit is indicated in more detail. The light reflected from thescanning beam is directed onto the cathode 150 which has a photoemissivesurface. The electrons emitted by the cathode are attracted to the firstaccelerator dynode 151 which has a surface which is a good secondaryelectron emitter. Successive dynodes 151 are maintained atcorrespondingly higher voltage by means of dynode power supply 152 andbleeder resistors 153 so that the signal generated by the reflectedlight is progressively multiplied. The dynode voltage is suppliedthrough voltage divider 155 and conductors 156 and 157. The finalcollector dynode 160 is maintained at a potential above the high side ofthe dynode power supply 152 by the power supply 161 through conductors162 and 163, and 330,000 ohm resistor 164.

The photomultiplier output voltage appearing across the resistor 164 isapplied in parallel to the grids of the twin triode tube 165 byconductors 167 and 168. Plate voltage is supplied to both sections oftube 165 in parallel from power supply 161 through conductor 170. Thetube 165 is operated as a cathode follower and the output is taken fromresistor 171. It will be observed that switch 173 is arranged to groundeither side of the resistor 171 to the chassis of the instrument.

The purpose of the switch 173 is to make possible the counting of eitherthe black or white area of the photograph. When conductor 175 fromresistor 171 is grounded through conductor 176 with the switch 173 inthe position shown, the output is delivered by conductor 177 to the highside of the bias supply circuit. Since the bias supply resistor 179 thusprovides a negative bias voltage in conjunction with bias supply 180,the scanning head output from resistor 171 is shifted in the negativedirection. If, for example, the scanning head output swing is from plus10 to plus 130 volts and the bias supply introduces a negative voltageof 70 volts, the resultant swing at the pulse gate grid lead 182 will befrom minus 60 to plus 60 volts. If the gate grid cuts oil the gate tube184 at about minus 10 volts, any signal at the grid from minus 10 toplus 60 volts will open the gate. This corresponds to a signal at theresistor 171 between plus 60 to plus 130 volts. It is apparent that sucha signal would be produced while the phototube is scanning a surfacehaving a relatively high reflectivity, such as a white surface.

If the switch 173 is thrown to its lower position, the low end ofresistor 171 is grounded through conductor 177, while the high end ofresistor 171 is connected to the low end of the bias supply circuitthrough conductor 175. The bias potentiometer 179 now tends to introducea positive bias voltage, while the resistor 171 tends to introduce anegative signal to the grid of the gate tube 184. If the output swingfrom resistor 171 is from minus 130 to minus 10 volts, and if the biassupply potentiometer 179 is adjusted to give a positive bias of 70volts, the net swing on the grid of the gate tube 184 will again be fromminus 60 to plus 60. However, it will be apparent that only signals fromthe resistor 171 between minus 10 and minus 80 volts will open the gatefor a cutoff of minus 10 volts for gate tube 184. This signalcorresponds to a low reflectivity surface such as a black surface on thephotograph being scanned.

As seen in Figures 1 and 4, a knob 187 is mounted above the scannersection for operating the switch 173, while knob 188 controlspotentiometer 179. The countratio knob 190 may be used to cause onlypulse counter 29 in Figure 2 to be operated in one position, whilecausing both pulse counters 29 and 34 to be operated in the otherposition. The left knob 191 in Figures 1 and 4 may be used to controlthe output voltage of the electronically regulated power supplies whichfurnish power to some of the stages of the ECAR.

It will be apparent that the bias potentiometer 179 is eflective to varythe sensitivity of the pulse gate tube 184 to varying degrees ofreflectivity. if for example, only areas having very low reflectivitywere to be detected, the bias voltage supplied by the bias supplycircuit would be raised by adjusting potentiometer 179 with the switch173 in the lower blac position.

Pulse gate From the foregoing description of the scanning and pulsegenerator circuits, it will be understood that the cathode control grid190 of the pentode gate tube 184 is supplied with a signal from thescanning head by means of lead 182, While the pulse generator supplies astream of pulses to the signal grid 191 by means of conductor 60. Itwill be understood by those skilled in the art that if the cathodecontrol grid 190 is below cut-oif voltage, there will be no flow ofelectrons from cathode to plate and pulses from the pulse generator willnot appear in the tube output circuit. On the other hand if the cathodecontrol grid 190 is above cut-01f potential, the signal or plate controlgrid 191 will control the distribution of current between the controlgrid and plate so that the pulse generator signal is amplified in theplate output circuit. In the particular circuit illustrated, the gatepulses from the scanning circuit are substantially eliminated bydegeneration in the unby-passed cathode resistor 193. The amplifiedpulse generator signal is delivered to pulse shap ing circuit A throughconductor 194 and capacitance 195 from potentiometer 197 in the platecircuit. Voltage is supplied to the screen grids and plate by means ofconductors 199, 200' and 201 from power supply 202.

Since the signal delivered to the pulse shaping circuit A will benegative, no phase inverting circuit is necessary. The counting circuitsfollowing pulse shaping circuit A, indicated by reference numeral 205 inFigure 5, are identical to those hereinbefore described in connectionwith the total counting assembly and have been given correspondingprimed reference numerals.

Operation The operation of the described embodiment of my invention willnow be readily understood. Since the embodiment disclosed isparticularly adapted for obtain ing a numerical proportion indicatingthe per cent of wood or void in a stack of Wood, the operation will bedescribed as it would be applied to such a determination. However, itwill be understood that the principles and features of the presentinvention are readily utilized for many other determinations. By way ofexample, and not by way of limitation, the following other uses fallWithin the scope of the present invention:

1. Determining the ink covering on many types of printed matter such asbread-wrappers, posters, etc.

2. Determination of the area of an irregularly shaped object as found onaerial photographs. Area of land under tillage, timber stands (sometimesby species), and lakes and streams are examples.

3. Determining the area of the surface of a leaf, useful in the study ofthe effect of poisons, etc.

4. Making a blood count from a photomicrograph.

5. The dirt (count) for paper could be determined and the dirt speckscould be graded as to size and color.

Having secured a high contrast photograph of the ends of a stack of logsor the like, the positive of this photograph may be mounted on thescanner drum 18, the ends of the logs appearing as white areas on thephotograph. The ECAR is now placed in readiness for use by manipulatingthe main power switch 210 at the bottom of the ECAR, the counters arereset by means of button 141 or 141, the count-ratio knob 19% is turnedto ratio, the sensitivity knob 183 and the voltage dynode knob 191 aresuitably positioned, and the per cent black and the per cent white knob187 is turned to per cent white to measure the ratio of actual Wood tostack volume. The exciter lamp switch 71 is switched on so that thescanning spot appears on the drum.

The left axial scanning limit is selected by moving the scanner headuntil the spot of light impinges on the photograph at the left limit ofthe area to be scanned. The position of the pointer '73 relative to thescale 74 is noted and the procedure is repeated for the right scanninglimit on the photograph. The scanning control switch 64 being in itslimit indicator position, the drum is rotated until the spot of light ison the desired circumferential scanning limit on the photograph, andthen the knob 97 is turned to move the brush 57 to the margin 86 betweenthe conducting portion 83 and the non-conducting portion 84 of thecommutator drum 82 (Fig. 3), this position being indicated by the limitindicator bulb 103 (Fig. 4).

To begin scanning, the disengaged scanning head is moved until thepointer 73 is about /5 centimeter to the left of the left scanning limiton the scale 74'. The carriage drive is then reengaged and the scannerdrum motor is switched on by means of a switch 77. The scanner switch 64is switched to scanning position when the pointer '73 reaches the leftscanning limit on the scale 74-. When the scanning beam impinges upon awhite area of the photograph within the scanning limit, the signal fromthe scanning head will open the pulse gate 27 (Fig. 2) and pulses fromthe pulse generator 28 will be counted by the pulse counter 29. When thescanning spot impinges upon areas of low reflectivity, representingvoids between adjacent logs in the stack, no signal will be delivered bythe scanning head 32 to the pulse gate 27 and the pulse gate will remainclosed so that no pulses from the pulse generator 23 will reachthe pulsecounter 29. Whenever the scanning beam is within the scanning limits onthe photograph, the pulse generator 28 is delivering pulses to the pulsecounter 34. The blanking brush 36 operates to blank out the pulsegenerator 28 whenever the scanning beam is off the circumferentialscanning limits on the photograph. When the pointer reaches the rightscanning limit on the scale 74, the scanning switch 64 is actuated toblank out the pulse generator. The white area count may now be read fromthe electromechanical register 39 and from the electronic counter whilethe total scanning count is read on the electromechanical register 35and the electronic counter 115 (Fig. 5).

From this ratio, and the volume occupied by the stack, the actual volumeoccupied by solid wood can be computed, and from the density of thewood, the actual weight of the stack is readily determined.

if desired, by way of a test, the per cent of voids in the stack can bedetermined by turning the knob 187 to the per cent black position, andsuitably adjusting the sensitivity knob 138 if necessary.

While there has been described a particular form of pulse gate, it willbe understood that broadly the invention comprises varying any signalwhich is susceptible to a numerical count in accordance with the outputfrom a scanning head in such a manner that for outputs from a scanninghead outside a given range, no counting signal will arrive at the pulsecounter. Further, it will be apparent to those skilled in the art thatthe pulse generator can take many different forms and generate manydifferent signals, especially since the counting circuit can be utilizedto convert the counting signal into a suitable pulse signal or the likewhich can be counted by electronic counters. Essentially, therefore, thepulse generator furnishes a counting signal while the scanning headfurnishes an enabling signal, and the pulse gate acts as a coincidentsignal determining circuit for passing a suitable counting signal to acounting circuit only when the enabling signal is present.

Further, the present invention is not necessarily limited to thescanning of photographs, since it can be used in coniunction with otherobjects which can be suitably scanned whether photoelectrically or bymeans of an electron beam or the like. There is thus provided accordingto the present invention means for obtaining a numerical countindicating the proportion of the area of an object having propertieswithin a preselected range, comprising means for scanning said obiectand for generating a scanning signal in accordance with said properties,an electronic counting signal generator, an electronic coincident signaldetermining circuit receiving signals from said signal generator andfrom said scanning means, and a counting device connected to the outputof said coincident signal determining circuit, said coincident signaldetermining circuit passing countable signals from said signal generatorto said counting device upon coincident of signals from said signalgenerator and said scanning means, and said counting device beingactuated by counting signals traveling from said signal generatorthrough said coineident signal determining circuit.

While I have resorted to details in the description of my invention forthe sake of clarity, it will, of course, be understood that manymodifications with respect to the various details will suggestthemselves to those versed in the art, and I, therefore, contemplate bythe appended claims to cover all such modifications which fall withinthe true spirit and scope of my invention.

1 claim as my invention:

1. In combination, a rotary scanning drum, a photoelectric scanning headfor moving axially across said drum, 3. pulse generator, a coincidentsignal determining circuit connected with said pulse generator and withsaid scanning head, a pulse counter connected to the output of saidcoincident signal determining circuit, a commutator connected to saiddrum for rotation therewith, and a blanking brush cooperating with saidcommutator and connected to said pulse generator for electricallyinterrupting the pulse from said signal generator to said coincidentsignal determining circuit during a portion of each revolution of saidscanning drum.

2. In combination with. a photoelectric scanner tube, a cathode followercircuit connected to the output of said scanner tube, a cathode outputresistor in said cathode follower circuit, a power supply supplyingvoltage to said cathode follower circuit, conductor means connecting oneend of said output resistor to the said power supply, a pulse gate tubecontrolled by said scanner tube output, a bias supply resistor in thecontrol grid circuit of said pulse gate tube, and switch means forselectively connecting said one end of said cathode resistor to one endof said bias supply resistor and said other end of said cathode resistorto the other end of said bias supply resistor for selectively reversingthe polarity of the cathode resistor output to said pulse gate grid.

3. In combination with a photoelectric scanner tube, a cathode followercircuit connected to the output of said scanner tube, a cathode outputresistor in said cathode follower circuit, a power supply supplyingvoltage to said cathode follower circuit, conductor means connecting oneend of said output resistor to the said power supply, a pulse gate tubecontrolled by said scanner tube output, a bias supply potentiometer inthe control grid circuit of said pulse gate tube, and switch means forselectively connecting said one end of said cathode resistor to one endof said potentiometer and said other end of said cathode resistor to theother end of said potentiometer for selectively reversing the polarityof the cathode resistor output to said pulse gate grid, saidpotentiometer varying the sensitivity of said pulse gate tube to a givenscanner tube output voltage.

4. In combination, a rotary scanner drum having means for receiving andpositioning an object thereon having a surface to be scanned of anextent less than the circumference of said scanner drum whereby when theobject is wrapped about the periphery of said scanner drum, a portiononly of the periphery of the scanner drum underlies the surface to bescanned, a commutator drum for rotation with said scanner drum having aconducting surface with a generally axially extending margin and anopposite obliquely extending margin, a commutator brush movable axiallyof said commutator drum to intersect said oblique margin at a pointdisplaced from said generally axially extending margin by an anglecorresponding to the angle subtended by said portion of the scanner drumperiphery underlying the surface to be scanned, a signal generatorconnected with said commutator brush for control thereby, saidcommutator brush electrically interrupting the signal from said signalgenerator during a part of each revolution of said scanner andcommutator drums, whereby scanning is restricted to the surface to bescanned.

5. In combination, a scanning drum for receiving a sheet having asurface including a portion with given reflective properties whose areais to be determined, said sheet surface having a dimension less than thecircumference of said drum and wrapped around said drum with oppositeedges of the sheet surface in circumferentially spaced relation on thedrum, means responsive to said given light reflective properties, meansfor moving said responsive means relative to said drum in a helical pathto scan the surface of said sheet carried thereby, means operativelyassociated with said responsive means for generating a numerical countindicating the area of said portion of the sheet surface, and meanssynchronized with rotation of said drum for automatically disabling saidgenerating means during the portion of each revolution of saidresponsive means relative to said drum when said responsive means isscanning between the ends of said sheet surface.

6. In combination, a scanning drum for receiving a sheet having asurface including a portion with given reflective properties whose areais to be determined, said sheet surface having a dimension less than thecircumference of said drum and wrapped around said drum with oppositeedges of the sheet surface in circumferentially spaced relation on thedrum, means responsive to said given light reflective properties, meansfor moving said responsive means relative to said drum in a helical pathto scan the surface of said sheet carried thereby, means operativelyassociated with said responsive means for generating a numerical countindicating the area of said portion of the sheet surface, means fordisabling said generating means during the portion of each revolution ofsaid responsive means relative to said drum when said responsive meansis scanning between the ends of said sheet surface, and second means forgenerating a nu merical count proportional to the area of the entiresurface of said sheet and controlled by said disabling means forinterrupting counting during scanning between the ends of said sheetsurface, whereby the proportion of the area of said surface having thegiven reflective properties may be determined.

7. In combination, a rotary scanning drum, a photoelectric scanning headfor moving axially across said drum, a signal generator for generating aseries of electric pulses, a coincident signal determining circuitconnected with said signal generator and with said scanning head, apulse counter connected to the output of said coincident signaldetermining circuit, and means for interrupting the series of electricpulses from said signal generator to said coincident signal determiningcircuit during a portion of each revolution of said scanning drum.

References Cited in the file of this patent UNITED STATES PATENTS1,195,583 Henretta Aug. 22, 1916 2,138,668 Stewart Nov. 29, 19382,184,162 Stockbarger et al Dec. 19, 1939 2,222,069 Cook Nov. 19, 19402,356,761 Jones et a1 Aug. 29, 1944 2,360,883 Metcalf Oct. 24, 19442,398,904 Libman et a1 Apr. 23, 1946 2,580,941 Morrison Jan. 1, 1952FOREIGN PATENTS 371,618 Germany Mar. 17, 1923

